Yan L, Shen Z, Lu Z
Lab of Animal Physiology and Biochemistry, Nanjing Agriculture University, Nanjing, China.
Dairy Herd Improvement Center, Henan Province Bureau of Animal Husbandry, Zhengzhou, China.
J Anim Physiol Anim Nutr (Berl). 2018 Apr;102(2):e569-e577. doi: 10.1111/jpn.12798. Epub 2017 Oct 13.
Na /H exchanger (NHE), which catalyses the exchange of extracellular Na for intracellular H , is of importance in the maintenance of Na and pH homoeostasis for rumen epithelial cells. Studies in ruminants showed that high concentrate diets could increase the expression of NHE in ruminal epithelium. Results of recent studies further indicated that insulin, as an important hormone closely related to dietary concentrate, could enhance the expression of NHE. In this study, we have investigated the mechanisms of insulin regulating the expression of NHE in rumen epithelial cells and its potential role in dietary modulation of NHE expression in ruminal epithelium of cows. In primary culture, insulin increased phosphorylation of ERK 1/2 and AKT in rumen epithelial cells. However, this promotion was diminished by insulin receptor inhibitor. Insulin also stimulated NHE1 and NHE3 expression. But this increase was suppressed by insulin receptor inhibitor, ERK inhibitor and AKT inhibitor. In the present animal experiment, NHE1 and NHE3 expression increased in rumen epithelium of cows ingesting a high concentrate diet (HC, 60% concentrate), accompanied by increased insulin concentration in plasma, compared to those feeding a low concentrate diet (LC, 20% concentrate). Furthermore, the phosphorylation of ERK1/2 and AKT was higher in the rumen epithelium of the HC group than those in the LC group. Collectively, these results indicate that diet-dependent change of NHE1 and NHE3 abundance was mediated, at least in part, by plasma insulin through the ERK and AKT pathway.
钠/氢交换体（NHE）催化细胞外钠与细胞内氢的交换，对维持瘤胃上皮细胞的钠和pH稳态具有重要意义。反刍动物研究表明，高浓度日粮可增加瘤胃上皮中NHE的表达。近期研究结果进一步表明，胰岛素作为一种与日粮精料密切相关的重要激素，可增强NHE的表达。在本研究中，我们研究了胰岛素调节瘤胃上皮细胞中NHE表达的机制及其在奶牛瘤胃上皮NHE表达的日粮调节中的潜在作用。在原代培养中，胰岛素增加了瘤胃上皮细胞中ERK 1/2和AKT的磷酸化。然而，胰岛素受体抑制剂可减弱这种促进作用。胰岛素还刺激了NHE1和NHE3的表达。但这种增加被胰岛素受体抑制剂、ERK抑制剂和AKT抑制剂所抑制。在本动物实验中，与低精料日粮（LC，20%精料）的奶牛相比，采食高精料日粮（HC，60%精料）的奶牛瘤胃上皮中NHE1和NHE3的表达增加，同时血浆胰岛素浓度升高。此外，HC组瘤胃上皮中ERK1/2和AKT的磷酸化水平高于LC组。总体而言，这些结果表明，NHE1和NHE3丰度的日粮依赖性变化至少部分是由血浆胰岛素通过ERK和AKT途径介导的。
